Essentially, an ignition interlock is a device that includes a breathalyzer which prohibits a vehicle from starting if the breathalyzer returns a reading of “under the influence” (i.e., corresponding to a statutory level of impairment or even a lower level of impairment prescribed by the manufacturer). Several courts throughout the U.S. are now requiring that interlock devices be placed in vehicles operated by individuals convicted of DUI offenses. The “LIFESAFER”™ ignition interlock system of the LifeSafer Interlock company (Cincinnati, Ohio) is a well-known conventional example. In it, a buzz tone is emitted during a breathalyzer test to indicate when a deep breath sample containing alveolar air has been provided and, thus, is sufficient to be analyzed.
It has been found that a major drawback of conventional interlock devices is that they might not be effective in deterring DUI offenses if an individual other than the defendant (i.e., the person who has been assigned the interlock device) actually operates the interlock. For instance, a defendant who is once again “under the influence” still might be able to operate the vehicle by asking his/her friend or spouse to supply a “clean” breath sample that will unlock the ignition.
A general solution that has been sought to eradicate this “loophole” has been to require an original “breath pattern” from the defendant against which subsequent attempts to unlock the ignition are compared; this helps thwart the occurrence of non-genuine breath samples. Examples of such an arrangement is disclosed in U.S. Pat. Nos. 4,738,333, 4,912,458 and 4,901,058. However, this solution has been found to present numerous difficulties and drawbacks. For instance, accuracy in comparing “breath patterns” can be highly elusive.
U.S. Pat. No. 6,229,908 discloses an ignition interlock system in which an individual's fingerprint may be used to verify his/her identity and blood-alcohol content is determined using spectroscopic analysis of the finger from which the fingerprint is obtained. Aside from cost considerations, a major drawback to such a device is that for purposes of motor vehicle operation, state statutes specify the manner in which blood-alcohol content is to be determined and spectroscopic analysis is generally not so specified. Rather, the use of a breathalyzer is typically called for. It would not be sufficient to use fingerprint authentication for interlock devices, because as discussed above, the defendant may provide the authentication while someone else supplies a “clean” breath.
A need has therefore been recognized in connection with providing an effective, foolproof ignition interlock device that precludes loopholes of the type described above.